Optical rotatory power. II.—The calculation of the rotatory power of a molecule containing four refractive radicals at the corners of an irregular tetrahedron

Abstract

It has been shown in the previous paper that, where there are four refractive centres arranged dissymmetrically in a molecule, there is a definite rotatory power depending on the dimensions of the molecule. In the simple active molecule of four different radicals we seem to have been provided directly with four different refractive centres. It is, however, necessary to examine if a chemical radical fulfils all the properties which were assigned to the hypothetical particle in the general calculation; but, if this true, we can substitute dimensions of such a molecule in the general formula to device a simpler formula for the rotation. If the radical is to have the same properties as the polarizable particle, it will have a definite refractivity for a fixed wave-length and its electric field in the polarized state must approximate to that of a dipole of equal value situated at its centre. A chemical radical has a definite refractivity for a given frequency, but it is only if the radical is small and fairly compact that its ield in the polarised state may be taken as that of a dipole concentrated at a single point. Consequently this paper will be limited to the calculation for molecules containing radicals of only a few atoms in length. The refractive properties will be regarded as concentrated at the geometric centre of these small radicals.